Recently, an attempt is made to dramatically enhance the operation speeds of LSIs as the performances of electronic devices such as bipolar transistors and field effect transistors are enhanced. With the enhancement, a problem of erroneous operation due to electromagnetic noise and the limitation in the operating speed of an electrical wire used for connection between electronic devices occurs. Particularly, improvement of the definition of a display device and an increase in the amount of video data make the above problem more significant. In order to cope with the problem related to the wire, some optical wiring devices that transmit signals by means of light are proposed.
Further, an optical communication system in which the power source of an optical device is turned on only when connection between the electronic devices is correctly made is proposed (for example, JP-A 2004-350155(KOKAI)).